In a variety of circumstances it is desirable for animals to have coats with short hair. This is particularly useful in relieving heat stress in some animals. There are also instances when short hair is preferred for cosmetic and/or allergenic reasons.
Heat tolerance is an important trait in large livestock, particularly cattle. Heat kills thousands of cattle per year in the United States, reduces performance of cattle and prevents the highest performance breeds from being used in hot climates. One method for reducing heat stress in cattle is to shorten hair. In cattle, a short-haired coat is referred to as a ‘slick’ coat, the associated gene is called the SLICK gene, and the phenotype of a short-haired coat is called “slick phenotype”.
Some cattle producers shave their cattle in the summer to improve heat tolerance; however, this method is extremely labor intensive, expensive and impractical for large herds. The Slick phenotype is found naturally in some cattle breeds of West African extraction, including Senepol, Carora, and Romosinuano; however, these breeds otherwise have modest performance and carcass qualities that limit their utility in the cattle industry.
The genetic basis for slick phenotype was identified as a single gene dominant (Olson et al. (2003), J Anim Sci.; 81(1):80-90). Traditional linkage analysis located the responsible gene to a 5 million base-pair region of cattle chromosome 20 (Mariasegaram et al. (2007), Anim Genet.; 38(1):54-59). The region was further narrowed using a genome wide associational study (GWAS) study (Huson et al. (2014), Front Genet.; April 29, Vol. 5:101). However, the narrower region contained few genes, none of which contained a mutation. Therefore, the narrowing was probably an error.
The ability to maintain homeostasis under heat stress is particularly important for cattle in subtropical and tropical regions. Although variation in heat tolerance among breeds has been studied for many years, relatively few efforts have been directed toward elucidating the mode of inheritance involved in heat tolerance. Variation in body temperature under heat stress has been studied in Australia and has been shown to have a low to moderate heritability (Turner, 1982; 1984; Mackinnon et al., 1991; Burrow, 2001). Also, Senepol cattle have been reported to be equal in heat tolerance to Brahman cattle (Hammond and Olson, 1994; Hammond et al., 1996) and Senepol F1 crossbreds with temperate breeds show heat tolerance comparable to those of Brahman and Brahman crossbreds (Hammond and Olson, 1994; Hammond et al., 1996; 1998).
Until now it was not known what mutation was responsible for the slick coat phenotype.